Study On Different Proportion Of Weakly Cohesive Coal Participating In Coal Blending And Coking

The reserves of weakly cohesive coal account for a large proportion in China.According to the coal rock blending theory,an appropriate proportion of these coals can be selected to blend into coking coal to produce coke products with better quality.Therefore,combined with the common coking coal resources of a coking enterprise,different proportions of weakly cohesive coal are mixed to carry out proximate analysis,micro coal rock characteristics,process properties,infrared spectrum,thermogravimetric analysis and crucible coke experiment.The effects of the blending ratio of weak cohesive coal on the adhesion,pyrolysis characteristics and coking performance of coal samples are analyzed and discussed,and the effects of coking process conditions on coke quality are studied.The results show that:（1）Long flame coal ash and sulfur content are low,M_ad is high,vitrinite content is the lowest,vitrinite content of lean coal is the highest,and there is no exinite in lean coal.There are obvious absorption peaks at 2923 cm^-1,2850 cm^-1 and 720 cm^-1 for lean coal and long flame coal,which are the anti symmetric,symmetric and stretching vibration of methylene chain CH₂;The absorption peak of lean coal is obvious at1630 cm^-1（stretching vibration of benzene ring）,and the aromatic ring structure is rich.（2）When the proportion of long flame coal is within 4%,it has little effect on the technological indexes of coking coal and fat coal.When the proportion increases to5%,the indexes such as G value,expansion b value,total expansion and Y value deteriorate seriously.When the proportion of lean coal is less than 7%,the process property index of blended coal is still excellent.（3）The blending of long flame coal can reduce the weight loss rate of coal samples of coking fat coal in the temperature range of 350-650℃,improve the pyrolysis behavior of coking fat coal,reduce the maximum pyrolysis rate R_max and activation energy E_a of coking fat coal,move T_max to the high temperature zone,greatly reduce the pre exponential factor of coking coal and reduce the yield of coal and coke.Blending lean coal into coking fat coal for pyrolysis has little effect on the activation energy of coking fat coal,but greatly reduces the pre exponential factor of coking fat coal,so that the main pyrolysis weight loss peak tends to move in the high temperature section.（4）When the proportion of long flame coal in coking coal is less than 4%,the thermal properties and micro strength of crucible coke decrease slightly.When the proportion increases to 5%,the quality indexes of crucible coke deteriorate rapidly.When the proportion of lean coal in coking coal is less than 7%,the quality index of crucible coke fluctuates slightly within a certain range.The deterioration of OTI index by the blending of long flame coal is mainly reflected in the increase of isotropic structure of coke,and the deterioration of OTI index by the blending of lean coal is mainly reflected in the increase of fine-grained mosaic structure of coke.（5）With the increase of final coking temperature,various quality indexes of coke refined from coking coal and fat coal show an optimization trend,reactivity decreases,strength and micro strength increase after reaction.When the temperature maintenance time of coking coal is controlled within 120 min,the coke quality becomes better with the increase of temperature maintenance time.When the temperature maintenance time increases to 180 min,the coke quality indexes are seriously degraded.With the increase of coking temperature maintenance time of fat coal,the coke quality index is more and more excellent.